One special issue when operating a battery of coking ovens having oven chambers that are charged with compressed-coal blocks lies in the fact that, for charging, the oven chamber must be open on the machine side of the battery of coking ovens. While charging compressed-coal blocks into the oven chamber that has a temperature of about 1000° C. so-called byproduct gases that contain unhealthy components form spontaneously. Unless suitable countermeasures are implemented, with each opening of the oven chamber, an intolerable environmental problem is created.
In practical applications, it has been tried to resolve the above-described problem by aspirating a part of the byproduct gases into a crude-gas manifold connected to the oven chambers. This concept provides that, first, a part of the byproduct gases is supplied to a gas-treatment system together with the crude gases generated during the coking process inside the closed oven chambers, the gas-treatment system comprising at least one gas scrubber. The action of drawing off byproduct gases from the opened oven chamber can be effected by bypass pipes used for routing the incident byproduct gases into one of the neighboring oven chambers, and from there they reach the crude-gas manifold. However, practical experience has shown that the described measures are not useful for ensuring compliance with tightened environmental requirements.
The pressure inside the oven chambers of batteries of coking ovens with so-called bulk operation, having oven chambers that are filled with coal from above and through filling openings in the ceiling of the oven, is at times controlled individually, the crude-gas manifold of the battery of coking ovens being operated at a slight partial vacuum. When filling the oven chambers, the partial vacuum of the crude-gas manifold is used to draw off any byproduct gases that form and supply them to the gas treatment means. Insofar as this method is transferred to batteries of coke ovens where the oven chambers are charged with compressed-coal blocks, though it is possible to reduce visible emissions when charging the oven chambers, this operation results, however, in impermissibly high oxygen concentrations in the crude gas. There is no shortage of attempts to shield the openings on the oven chambers during the charging operation with hoods in order to minimize entry of environmental air into the system. However, these efforts have been without success. The air that gets in during the suction operation through the opened oven chamber can cause the automatic deactivation of the fine tar separator operating electrostatically. Moreover, proof has been found to indicate that reactions of oxygen with other components of the crude gas result in the formation of chemical compounds deposit in the pipes of systems downstream, thereby considerably restricting the use of the coke-oven gases produced during the coking operation for heating typical industrial furnaces and/or rendering their use impossible altogether. A further disadvantage that results from any intensive aspiration of the byproduct gases in the crude gas system is the fact that, due to so-called “carry-over,” it is possible for fine particles to enter the crude gas during the filling operation and collect in containers and the piping systems of the gas-treatment system producing a negative influence on the quality of the tar that is obtained from the gas treatment.
DE 2 238 372 [GB 1,387,962] relates to batteries of coking ovens with oven chambers that are filled from above with coal through fill openings in the oven ceiling. The oven chambers can be optionally connected to two manifolds, one manifold serving for drawing off the production gas and the other for aspirating the byproduct gases. Dust is removed from the suctioned-off byproduct gases inside a gas scrubber, and the gas is cleaned of any tar components.